intel/skylake: implement vboot_platform_prepare_reboot()

In order to not reboot loop in the face of failed vboot verification
on resume set the PM1 control register to indicate S5. After the
subsequent cold reset the PM1 control register will indicate S5
as it should.

BUG=chrome-os-partner:46049
BRANCH=glados
TEST=On chell injected failed vboot verification. Ensured a reboot
     loop doesn't ensue.

Change-Id: Ie5e9e3f6441a217a5e02b4d78aaf21f8249b8a43
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: a63b57d7bc59bcaf5518f7cc4afccd3d5da6df1c
Original-Change-Id: I5e467854bf065a138bd46e476a7e7088f51454ca
Original-Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/323504
Original-Reviewed-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Reviewed-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: https://review.coreboot.org/13579
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

1 files changed, 14 insertions, 0 deletions

diff --git a/src/soc/intel/skylake/romstage/power_state.c b/src/soc/intel/skylake/romstage/power_state.c
index cbef09a96c..19875346b4 100644
--- a/src/soc/intel/skylake/romstage/power_state.c
+++ b/src/soc/intel/skylake/romstage/power_state.c
@@ -158,3 +158,17 @@ int vboot_platform_is_resuming(void)
 	int typ = (inl(ACPI_BASE_ADDRESS + PM1_CNT) & SLP_TYP) >> SLP_TYP_SHIFT;
 	return typ == SLP_TYP_S3;
 }
+
+/*
+ * The PM1 control is set to S5 when vboot requests a reboot because the power
+ * state code above may not have collected it's data yet. Therefore, set it to
+ * S5 when vboot requests a reboot. That's necessary if vboot fails in the
+ * resume path and requests a reboot. This prevents a reboot loop where the
+ * error is continually hit on the failing vboot resume path.
+ */
+void vboot_platform_prepare_reboot(void)
+{
+	uint16_t port = ACPI_BASE_ADDRESS + PM1_CNT;
+
+	outl((inl(port) & ~(SLP_TYP)) | (SLP_TYP_S5 << SLP_TYP_SHIFT), port);
+}